Unfortunately I cannot see the units or numbers clearly to give you a precise measurement. I presume for question a) the volume decreased because the expiratory reserve volume is now lower than the inspiratory reserve volume. This means the person is inhaling more than exhaling, but there seems to be some sort of air leakage. Possible the diaphragm relaxed so lung pressure increases due to rib cage closing in, so the lung cannot be expanded. Aka shortness of breath.
e) in order to know/detect exercise is to see the tidal volume (breath in and out in one cycle) increasing to show rapid breaths for oxygen supply to meet oxygen demand.
If you struggle with these type of questions i suggest watching short videos with a graph next to it, to show the person breathing in and out, with labelled terms eg. vital capacity.
I hope that helps : )